22 Feb
2011
22 Feb
'11
11:47 a.m.
That manual also covers the LK250 in some detail.
Possibly not
Is it an LK250 or an LK201? The latter goes with the VT220, etc. The
former from what I refall is the PC/AT compatible keyboard with much the
smae layout.
enoguh detail to fix it, but I *think* the schematics
are up on
bitsavers (perhaps part of another manual, I'm sure I've seen
them somewhere).
I reverse-engieered it years ago. It's very simple. An 8051
microcontrolelr, a couple of TTL decoders, RS232 level shifter and a 7805
regualtor basically. And the membrane keybaord assembly.
How hard can it be to fix a keyboard ?
Well, the mcirocontroller is custom-programmed... The membrane assembly
(whcih is what normally fails) is heat-staked toether. You can unclip
all the keycaps but that doens't do you a lot of good. Yes, you can cut
away the heat stakes and take the whole lot apart, but how on earth do
you get it to stary reassembled. There isn't enough plastic left to form
the mins over for a second time
-tony